Industrial robot control apparatus

ABSTRACT

An industrial robot control apparatus for teaching an industrial robot and operating the robot in accordance with the teaching comprises a teaching handle (9) having a teaching switch (10), and a brake release switch (11) and a sequence control circuit (1). When the operator grips the teaching handle (9), the brake release switch (11) is activated, whereby a servo amplifier (6) is brought to an emergency stop condition in response to a signal from the switch, and a dynamic brake and a mechanical brake are released.

TECHNICAL FIELD

The present invention relates to an industrial robot control apparatusfor controlling paint robots and the like, and more particularly, to anindustrial robot control apparatus able to carry out a safe, accurateteaching of a robot.

BACKGROUND ART

To operate a paint robot or the like, the operator holds a paint gun,teaches the required movements of the gun to the robot, and causes therobot to store the taught movements and to carry out the paintingprocess in accordance with those stored movements. During the teachingoperation, vectors of force are detected by a force sensor attached tothe distal end of a robot arm, and are decoded by a control apparatus,which then causes the robot to act in the directions of the vectors.

In this system, however, since the robot is controlled by the controlapparatus, an incorrect operation by the operator or a malfunction ofthe robot control apparatus may place the operator in danger, despitethe low speed of the operation.

Further, since the robot is operated in the directions of the vectors offorce detected as described above, the reactions of the robot during theoperation are very slow, and thus a delicate positioning movement andaccurate teaching are difficult.

DISCLOSURE OF THE INVENTION

The object of the present invention is to provide an industrial robotcontrol apparatus which solves these problems, and is able to carry outa safe, accurate teaching of a robot.

To solve the aforementioned problems, according to the presentinvention, there is provided an industrial robot control apparatus forteaching an industrial robot and operating the robot in accordance withthe teaching, which comprises

a teaching handle having a teaching switch and a brake release switch,

a sequence control circuit able to bring a servo amplifier to anemergency stop condition, to thereby release a dynamic brake of aservomotor and release a brake, in response to a signal from the brakerelease switch, and

a teaching memory means for storing taught positions through theoperation of the teaching switch.

According to the present invention, to begin a teaching operation, firstthe operator grips the teaching handle, whereby the brake release switchis activated and the servo amplifier is brought to an emergency stopcondition in response to a signal from the switch, so that an outputfrom the servo amplifier to the servomotor is cut off, and thus theservomotor is in a dynamically braked state.

Namely, the sequence control circuit releases the dynamic brake, andalso releases the brake.

Accordingly, the operator is able to operate the robot as desired andteach required movements to the robot, and the robot stores the taughtpositions through operation of the teaching switch.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an industrial robot control apparatusaccording to one embodiment of the present invention; and

FIG. 2 is a diagram showing details of a teaching handle.

BEST MODE OF CARRYING OUT THE INVENTION

One embodiment of the present invention will now be described withreference to the drawings.

FIG. 1 shows a block diagram of an industrial robot control apparatusaccording to one embodiment of the present invention. In FIG. 1, numeral1 denotes a sequence control circuit for controlling output to aservomotor and the like; 2 denotes an auxiliary brake control circuitwhich supplies power to a brake, described later; 3 denotes a relay fordisconnecting a dynamic brake of the servomotor; 4 denotes a relay forswitching the brake control to an automatic or manual mode; 5 denotes anamplifier power circuit which supplies power to a servo amplifier 6; 7denotes a main brake control circuit for controlling the brake; and 8denotes an intrinsically safe circuit, which lowers the voltage,current, etc., of signal lines below the level at which arcing willoccur, to prevent explosions caused by an ignition of an evaporatedsolvent in a paint robot or the like, caused by sparking at electricalcontacts therein.

Numeral 9 denotes a teaching handle provided with a teaching switch 10and a brake release switch 11. When teaching required movements to therobot, the teaching switch 10 is operated at a certain point and therobot control apparatus then stores this point. To carry out theteaching operation, the operator grips the teaching handle 9 to activatethe brake release switch 11 and release the brake described later. Theteaching handle 9, the teaching switch 10, and the brake release switch11 will be described in detail later.

Numeral 12 denotes a servomotor for driving the robot. Although aboutthree to six servomotors are actually used, only one is shown and theothers are omitted for simplicity. Numeral 13 denotes a brake, which isused to brake the shaft of the servomotor or a robot-side rotatingshaft. As in the case of the servomotors 12, although each servomotor 12is provided with a brake 13, only one of the brakes 13 is shown and theothers are omitted for simplicity. The brake 13 is released when anelectric current is supplied thereto, and operated when the electriccurrent supply is cut off.

FIG. 2 shows details of the teaching handle. In FIG. 2, numeral 9denotes the teaching handle, which is fixed to a torch 15, and 10denotes the teaching switch. During the teaching process, the operatordepresses the teaching switch 10 at a certain point and this taughtpoint is stored in the robot control apparatus. Numeral 11 denotes thebrake release switch 11. To start the teaching process, the operatorgrips the teaching handle 9 and the brake release switch 11 is thenactivated by the pressure of the operator's grip. Numeral 16 denotes apaint discharge port.

Namely, when the operator grips the teaching handle 9 to start theteaching process, the brake release switch 11 is activated to bring theservo amplifier 6 to an emergency stop condition, and thus the teachingprocess can be carried out safely and easily.

The control of the sequence control circuit 1 when carrying out theteaching process will be described with reference to FIG. 1. When theoperator grips the teaching handle 9 to start the teaching process, thebrake release switch 11 is activated and a signal is output to thesequence control circuit 1, which then sends an emergency stop signal tothe amplifier power circuit 5. The amplifier power circuit 5 then stopsthe supply of power to the servo amplifier 6, and thus a control currentsupplied by the servo amplifier 6 to the servomotor 12 is cut off.

When the amplifier power circuit 5 is brought to an emergency stopcondition, the servo amplifier 6 brings the servomotor 12 to adynamically braked state. This is achieved by short-circuiting thewindings of the servomotor 12, by a resistor inside the servo amplifier6. At this time, however, since an arm of the robot is in a dynamicallybraked state, a large resistance is imposed during operation of therobot arm. To remedy this situation, the sequence control circuit 1turns off the relay 3, to thereby release the dynamic braking of theservomotor 12.

At this point, since the main brake control circuit 7 is in an emergencystop condition, the current flow to the brake 13 is cut off to releasethe brake. At this time, the arm of the robot cannot be moved, and thusthe relay 4 is switched to allow manual control and is connected to theauxiliary brake control circuit, whereby current is supplied from theauxiliary brake control circuit to release the brake.

In this state, the current flow to the servomotor is cut off, and thusthe arm of the robot cannot move and endanger the operator. Further,since the dynamic brake and the brake are released, the operator cansafely and accurately carry out the teaching process by depressing theteaching switch 10 at each teaching point, whereby the taught point ismemorized by the robot control apparatus.

According to the present invention, as described above, the controlapparatus side is brought to an emergency stop condition by activatingthe brake release switch of the teaching handle, to thereby cut off theoutput to the servomotor and release the dynamic brake and the brake,and thus the teaching process can be carried out safely and accurately.

I claim:
 1. An industrial robot control apparatus for teaching anindustrial robot and operating the robot in accordance with theteaching, comprising:a teaching handle having a teaching switch and abrake release switch; a servomotor; dynamic brake means for saidservomotor; a mechanical brake for said servomotor, said mechanicalbrake being released when an electrical current is supplied thereto andoperated when the electric current is shut off; a servo amplifier; asequence control circuit operable to bring said servo amplifier to astop condition and to release said dynamic brake and said mechanicalbrake in response to a signal from said brake release switch; andteaching memory means for storing taught positions through the operationof said teaching switch.
 2. An industrial robot control apparatusaccording to claim 1, wherein said brake release switch is activatedwhen an operator grips the teaching handle.
 3. An industrial robotcontrol apparatus according to claim 1, which includes an auxiliarybrake control circuit for supplying electric current to said mechanicalbrake to release said mechanical brake in response to said signal fromsaid brake release switch.
 4. An industrial robot control apparatusaccording to claim 1, which includes an intrinsically safe circuit forlowering the voltage and current of signal lines below the level atwhich arcing will occur.